I agree that optimizing and reducing water consumption will alleviate water shortages. But I do wonder: given how the population of the US southwest is growing

I agree that optimizing and reducing water consumption will alleviate water shortages. But I do wonder: given how the population of the US southwest is growing every year, how long can water optimization last? Today, California has 38 million residents, and by 2050 is projected to reach 60 million. Will optimization be enough to provide water for 20 million additional inhabitants? If the population keeps growing, will optimization be enough in the year 2100? And onwards? After a certain point it's not possible optimize any more and new water sources are needed.